Electric relay



May 3, 1938. J. E. CARLSON ELECTRIC RELAY Filed July 25, 1956 RNEY INVENTOR JOQ:%:RLSON,

E m w Patented May 3, 1938 UNITED STATES PATENT ()FFIICE ELECTRIC RELAY necticut Application July 25, 1936, Serial No. 92,484

4 Claims.

My invention relates to a device of the gen eral character shown and described in Getchell Patent No. 1,681,851 for protecting electrical circuits. This particular invention is directed to a device especially intended for use in an independent coil circuit or other system having independent terminals and in which a secondary circuit may be opened by changes taking place in a main motor circuit and closed manually or opened and closed manually.

One object of my invention is to provide a relay in which a secondary circuit is opened automatically in response to overload conditions in the main circuit and yet when the circuit is I opened will remain open until the relay is manually reset.

Another object is to provide a relay device which can be readily inserted into and removed from the independent terminal clips of the main and secondary circuits.

Another object is to provide a device of this character in which an insulating housing supports the main and separate secondary circuit terminals and yet is simple and compact in 5 structure.

Another object is to provide such a thermostatic relay having a spring pressed switch member held in the closed circuit position between the secondary circuit contacts.

30 Another object is to provide a device of this character with simple and external means for positively resetting the parts.

My invention contemplates a relay having a housing, with main motor terminals, a pair of 35 separate secondary circuit terminals and contacts carried by the housing, a thermostatic element, and a heater strip positioned so as to influence the thermostatic member. A pivoted snap switch member bridges the contacts which are connected to the secondary terminals when the circuit is closed. A push button is provided for moving the pivoted switch member into circuit closing position and may also be used for opening the circuit.

Fig. 1 is a plan viewof one form of relay em bodying my invention.

Fig. 2 is a longitudinal sectional view of the same.

Fig. 3 is a transverse sectional view in the plane of the line 3-3 of Fig. 2.

Fig. 4 is an exploded perspective view of certain elements of the construction.

' The main housing is preferably formed of two parts I. and 8 formed of insulating material. These parts are held to ether by cylindrical caps 9 and 10 which form the main terminals of the relay and are adapted to fit into the usual clips or other mounting terminals (not shown). An extension 1 formed integrally with the part I of the housing projects laterally.

A heater strip or wire II is mounted in the main housing with its flanged ends suitably connected to the terminals 9 and ID for instance by screws l2 and l3'so that this heater constitutes a part of the main conducting circuit of the 10 system.

Terminals l4 and i5 are mounted on the extension and are secured by the insert members l6 and. I1, respectively. These terminals are of inverted U-shape and are adapted to engage 15 terminal clips of any suitable form (not shown).

The secondary switch includes a relatively stationary but adjustable contact l8 and a resilient switch' member 19 secured to the member H. The contact i8 is preferably in the form of a 20 screw so that it may be adjusted. The resilient switch member l9-is L-shaped and has one end clamped between the secondary terminal l5 and its supporting member 11. The other end of the member l9 extends through an opening in the extension and is positioned adjacent the contact I 8.

A movable switch lever member 20 is pivotally supported by' a hinge pin 24 on the end of a bimetallic thermostatic arm 2i. One end of this arm is secured to the upper part of the housing at one end by a screw 22 and its other end which carries the switch member is free and extends into the center of the housing. A spring 23 is mounted on the pin 24 on the side of the switch member 20 with one end connected to the bimetallic strip 2| and its other end caught around the body of the switch member. This spring tends to turn the switch member 20 in a counterclockwise direction as viewed in Fig. 2. When the circuit is closed the contact tip of the member 20 bridges the space between the contacts l8 and 19 of the secondary circuit. When the circuit is open the shoulder 20' of the switch member 20 rests against the-free end of the thermostatic strip 2|.

The switch member 20 is provided with a curved arm 2| which extends through an opening in the shank 25 of an operator or push button 26. This shank is guided in a passage 21 in the extension I and is provided with an open-. ing 28 through which a part of the contact I9 extends.

A strip 29 of thermal insulating material such as asbestos is preferably interposed between the 'that most of the heat effect from the strip ll from the circuit through the strip is conducted through the washer on the screw 22 which is designed to produce the desired time 8.

When in use the parts are in the position shown in Fig. 2 with the circuit closed. In case of an excessive rise in current due to overload the thermostatic strip .2I is warped by the heat from the heater II, and the switch member 20 is thus disengaged from the contacts l8 and I9 whereupon the spring 23 snaps the switch member 20 to the open circuit position, in which position the parts will remain, even after the thermostatic strip cools off, until it is desired to reset the relay. Resetting is accomplished by simply pressing on the push button 26 which will bring the switch member 20 back into engagement with the contacts l8 and I9 and close the secondary circuit.

The circuit through the relay may be momentarily opened by pressing on the finger piece 26 sufflciently to tilt the switch member 20 (clockwise as viewed in Fig. 2). The upper end of the switch member will thus compress the resilient contact member I9 and move away from the contact l8 sov as to break the circuit. When the finger piece is released the spring 23 willreturn the switch member to the closed circuit position.

The spring contact l9 normally yields suiiiciently for the contact head of the lever member 20 to pass the tip of the screw l8. As pressure on the button 26 is released the spring strip 2| will raise the contact lever member 20 back to the position of Fig. 2. The only part of the lever member 20 which need be of conducting material is the head which connects the con tacts l8 and I9 by being wedged between them. This contact head may be electrically insulated l l in any suitable manner, for instance by forming the lever 20 of insulating material or by means of the insulating strip 29. Since the switch member I9 is resilient this contact member also assists the spring 23 in snapping open the circuit."

I claim:

1. In a relay, an insulating housing having cylindrical ends and a lateral extension between the ends, main terminal caps on the ends, a resistance heater electrically connecting said caps within the housing, secondary circuit terminals adjacent opposite ends of the extension, a contact connected to each secondary terminal and extending into the interior of the housing adjacent an outer wall thereof, a pivotal member bridging said contacts inside the housing and means responsive to the heater for sliding said pivotal member and its pivot away from the contacts to open the circuit.

2. In a relay, an insulating housing having main terminals on the ends, an extension on the housing, a resistance heater electrically connecting the main terminals, secondary circuit terminals adjacent opposite ends of the extension, a contact connected to each secondary terminal and extending into the interior of the housing from an outer wall thereof, oneof said contacts being rigid and the other resilient, a pivotal member having a contact wedged between said contacts inside the housing, and means responsive to the heater for moving said pivotal member and its contact from between the secondary contacts to open the circuit.

3. In a relay, an insulating housing having main terminals on the ends, an extension on the housing, a resistance heater electrically conmeeting the main terminals inside the housing, secondary circuit terminals adjacent opposite ends of the extension, an adjustable contact connected to one of said secondary terminals and extending into the housing, a resilient contact connected to the other secondary terminal and extending into the housing adjacent the adjustable contact, a pivotally supported switch member adapted to be clamped between said contacts inside of the extension, a bimetallic member responsive to the heater, and means of'connection between the pivotally supported switch member and the bimetallic member for withdrawing said switch member from between the contacts, said resilient'contact tending to angularly displace said pivotal switch member when it has been withdrawn enough to clear said adjustable contact.

4. A relay having a housing with main end terminals and a lateral extension, two independent circuit terminals mounted on the extension between the end terminals, a switch within the housing having a pair of contacts connected with the independent terminals, at least one of said contacts being resilient, a third switch contact adapted to bridge said pair of contacts, thermostatically actuated means Within the housing for actuating the third switch contact to open the circuit through the independent terminals upon a predetermined overload in the main circuit, and manually operable means between the independent terminals for actuating the third switch contact to close the circuit through the independent circuit and to open said independent circuit momentarily by moving said third switch contact against said resilient contact to stress it more than is done normally when the switch is closed.

JOHN E. CARISON. 

